Electric measuring instrument



July 31, l923- 1,463,597

w. M. SCOTT ET AL ELECTRIC MEASURING INSTRUMENT original med Jan. 2e, v1918 2 awww-sheet, 1

' cc, TAM/wwf Juny 31, 19,23. 1,463,597

W. M. SCOTT ET AL ELECTRIC MEASURING INSTRUMENT original Filed Jan. V.26; 1918 2 Sheets-Sheet? l/ AMPEn-RES Patented July 31, 1923.

narran sfr-fares AWALTER, M. SCOTT, or LAKEWOOD, Ann-nannten E. measles, or onEvnLAND, OHIO.Y

weiser Ferrier ferrite,

ELEcrRroiirEnsU-irus INSTRUMENT.

Application nieu, January 2e, isis, serial 1\To.21e,e5e Renewed. Januaryiosieaa, sei-iai No,52e,2o5.

i T all 'whom t may concern.'

Bel it 4known that we,i(l) YALTERM. Scor; and (2,)RALE1GH E.. Tn'nsrsn, citizens-ot the United- States,l residing.- at Lakewood `and Cleveland, re spectively,`V in the county of Cuyahoda/ and, Stateqf Ohio, have invented a certain new and useful mprovement in Electric Measuring Instruments, of which the following is a ful-l, clear, and exa-ct description, reference ,being had to the accompanying(ilrawings. v Thisfii'iventionrelates to electrical measuring instruments andhasparticular refera enceto smallnsized ammeter although the features ofconstruction hereafter described and claimedV arerequally applicable tovoltmeters The instrument illustrated and de!y scribed ,herein has `been developed with especia-l reference to useon the cowl-boards otA explosion engine vehicles to. show thejcharg-Y in-gjand discharging rate of the startingrand lightingr b atteryordinarily used inl such vehicles, though it will be understood that we do ,not,limit ourselves to this use,v Owing to the exposed p osition the extreme vibrac tion,y and the. in'diiferent care to, which such an instrument is Subjected2 its requirements are unusually. severe; added to which is the -requi'rementof .cheapness e i The, object-s of our invention.. are the ,pros vision of an instrument of 'thisgeneral na-` ture which shall be dead beet both under load andl under 1- vibration g Y which shall be freefromsprings, dash pets and otherdeli-l cate or closettingcontri'vances; which shallnot be injuredby vibration or hy a temporaryvoverloa-,d evenvup to twohun dredamperes, its maximum escale. capacitv':

which shall' have-a comparatively even scale; the obtaining of, all theseobjectstogether with the` further object of practical accuracy by means of a simple,v rugged, and inf expensive structure; while further objects and advantages of'our improvements will become apparentV as the description pro*- ceeds.

ent description,

'manet .fece and. Pel-reed These: vdrawings illustrate an ammeter,v

Figs. l and' Qbeing diagrammatic views: il-

lustrating the arrangement of the essential' elements.;A Fig. 3 is a*r perspective view of our improved a'mmeter tav-kenl from the rear; 4 kis ya back view offthe ,works oi' our` improved ammeterv; Figs. 5 and 6 arefcentrai sectional views through the.l complete @meter and Case ;Y Fie'- 7. is. a fee@ View Of the saidj ammeter, theyc'ase being omitted and part of the dial plate broken away; and

Fig. 8'is as separated`perspectiveview showingfthe various parts of theuammeter works.'V

'The essential elements@ our amriete consist of a permanent magnet, a" solenoidk 01,' Current@1051;A and 'a rilevabl@ -SyStieUfii09H1-` prising4 an armatureY whichr fis .subjected llo n0'de1 id'a1sof having e `lla meine device; and 1n, lts/(mere. generic-aspect the essence 0f Our .mventlnonslsts `111, locating, d

lehnen' bhe-magnet pole Said cell being formed' intwvo separated portions between whose projections saijdmag'net poles are located, The movable systemY comprises a sta traversing the space between the;magal Het poles i and "intersecting the current edilL its axis being perpendicular-to 'the field" of' the coil 'andtojthe planeet the magnet and tothe liv-ne joining` the magnet pole-s; .said

staff .an elongated,armature voflsoft iron or sotsteel secured thereto insideftheV limits of the coil' andraiso having pointer and @damping-device; said damping device consisting of a circular 'metaljdislr or cyli'n l derl carriedbyfthe staff between or yadjacent touthepmagnet poles, y Referring' to Figs. 'l 2, I represents the magnet, whichis made Ot substantially closed form having poles 2-j`2 Vfacing each other and deiining a rather 'nan row air a L The current Ycoil preferably g p i the portions 3 andV 4 being spaced apartyand arrangedhsubstantially, as shown, repref sents the. staff,V 7 the armature carried Athereby, `8' the damping member-ena@ .the

Vtends to resist rapid' or fviloratory movement .consists off a portion y3l and al portion-A` v spaced apart andg'connected by aportion5` of the pointer, its damping effect being produced partly by eddy currents induced in the metal and partly (when this member is made of iron as is preferable) by a displacement of the induced magnetism thereof which is opposed by the hysteresis. A coil being located outside of the magnet and having its separated portions arranged upon opposite sides of the poles, a very great over load of short duration, even as high as 200 amperes will have no demagnetizing effect upon the permanent magnet. The armature A including the magnetbody also), and also upon opposite sides of a plane which isperpendicular to the irst'plane andalso passes through the tivo poles. ln the construction illustrated the axis of the Ycurrent coil is parallel to the Vplane o-f the magnet body,

l but this, While desirable, is not imperative.

Now describing the preferredconstruction whereby these advantages are secured, 1() represents a circular plate of non-magnetic material having a peripheral rim 11. From the body of thisrplate there is struck up a frame part 12 having at `Vits end the legs I13 integrally connected with the plate andhaving at its middle point the projecting lug 14. This frame is bent vat right angles With the plate l0 and the lug 14:is turned over until it is parallel with the plate 10, said Vlug and the portion of the plate directly beiieath being formed with apertures or socketsll-l for the reception of' the stafl'l 6.

An'elongated metal bridge 17 has its ends turned to right angles as shown at 18-18 and again atright angles as shown at 19--19- Adjacent to each end the bridges-17 yis formed with an aperture 20 receiving the threaded studs'521--21 to which are secured the clips. 22, the same being` insulated from the meinberl/v by suitable washers 23. The endsof the current coil are attached to these clips in suchryvise that when the bridge 17- is secured to the plate 10 the portions 3 Vandes thereof will fall on opposite sides of thel frame 12, the portion 5 passing freely over the top of that frame. i

Inside the cup defined by the rim 11 is located the circular dial plate 25 which is secured in place by screws Q6 traversing the dial plate and base plate 10 and tapped into the portions 19 19 vhereby the entire de'- vice is held together. `The plates 101m d are formed with registering curvilinear apertures A2T-27 for the passage of the pointer 5).

lhe plate 10 is also forinedwith a pair with the lip 11l so as to lit snugly` in the interior of the cylindrical case 35 in which the Works are inserted, and are preferably formed with the threadedy apertures 36 receiving screws 37 by Which the Works area held in said case.' At its front side this' Ycase is provided with a transparent pane 38, and at its rear with a metal cover 39, suitably apertured forthe passage of the studs 2,1-21.. Nuts l10440 serve to securef this (cover in place, suitable insulating Washers being .interposed to prevent grounding or short circuiting of the parts, and the 'lead'.Wires 4277-42 are ,secured to said studs' by means of suitable thumbscrews Q -43.

In addition to the electrical and operating advantages secured by the ariangem'entfof the'essentia'l parts first' described, the detailed construction herein set forth canlall be made by stampings,veven te the magnet 1; the parts can be assembledr with a minimum of labor; absolute uniformityof output isY I secured; While the arrangement of the Works Wholly independentof the case permitsadjustment and calibration to be effectedv be fore the Works are applied Ato the' caseland While all parts of the same are accessible. The instrument. is proof against over-load, is not affected by any shocks or bloivsth'at the glass cover can withstand,v is highly dead-beat, gives practically equal deflections upon opposite sides of the Zero point, thus' showing charging. and discharging rates, and is lhighly accurate,

Y The damping effect can bev varied ividely by changing the size,shape', thickness mate-` ,v

rial and location of the damping member, since the larger the dimensions of this mem-v ber, either diameter or axial length, the more thisv member lof the softest-possibleiron so thatits residualmagnetism will be. small, although by suitably choosing its dimensions different qualities of steel canA alsobe employed. ln fact a non-magnetic metal. can be used Afor this member, but. with a. considerable loss of damping effect sincein that ease only the eddy currents are available to restrain motion, therer being ne hysteresis effect. The size of the armature must also beA adjusted in comparison With that of the damping member. lnasmucli as the size and magnetization of the-permanent magnet, the size, shape and material of the damping memberthe size, shape and material of the armature, and the distance of the armature 'marked its effect will be. l/Ve prefer to make and damping member from each other and u related, =it is obvious that a ychange 'infany one of ythese must be' balanced by a change 'elsl-nvhere,- but a, proper adjustment of these features 'can easily be effected v Within `Vthe 'scope 'of the explanation V'heretofore given. It will be understood that-'the Dimm-berief turns in the eurrentcoilcan be 4increased to any desired extent, and in fthe case vof a voltmeter will .necessarily be largely increased; alsothat'greatfchanges lin other details can bemade `Wi-tliou't departing from our invention and We do not limit ourselves to any details here pointed out except as specifically recited in the claims hereto anneXed. v

Having thus described our invention, What We claim is l. In an electric measuring instrument, in combination, a sheet metal base plate, a rectangular frame integral therewith and projecting perpendicularly therefrom, said frame having an overhanging part and said base plate having an aperture, a pivot bearing in said overhanging part, a second bearing in the base plate opposite thereto, a stati vjournaled in said bearings, a pointer carried by said staff and passing through said aperture, a permanent magnet carried by said base plate, an armature carried by said staff upon the opposite side of said magnet from said base plate, a bridge attached to said base plate, and a current'coil carried by said bridge, said coil being made in two spaced parts Which straddle said frame and embrace said armature but lie Wholly at one side of the magnet.

2. In an electric measuring instrument, in combination, a base plate having an aperture, a frame carried by said base plate at one side thereof, pivot bearings carried by said plate and frame respectively, a stati journaled therein and having a pointer which traverses said aperture, an armature carried by said stai, a bridge attached to said base member independently of said frame, and a current coil carried by said bridge, said coil being made in tiveY spaced parts which straddle said frame and embrace said armature.

3. In an electric measuring instrument, i combination, a base plate, a frame carried thereby, a staff pivoted thereto perpendicular te the plate, an armature carried by said.

stati', a bridge attached to said plate, a current coil carried by said bridge and made in tWo longitudinally separated halves adapted to straddle said frame and embrace said armature, and current terminals carried by said brid-ge.

4t. In an electric measuring instrument, in combination, a circular plate, a bridge attached to one side thereof and spaced therefrom. current terminals ,carriedv by said bridge, a current coil connecting said terminals and located at one side of said bridge,

sai-d 'fcofl' being formed -n'ftwo ,spaced l'portions `havin-g va common axis which is vparaillel to the face ef the plate, Fal iramegcar- 'ried' vby said plate independently loit said bridge, ay staff? pivotedin said frame, and an 'armature "carried by @said stati insidefthe its or said coil, the vtwo h'alves 'et 'sa-id-A coil 5k In anelectre measuring instrument, in y combination, a Vsheet metal base' l plata a and surrounding said armature.V

6. In an electric measuring instrument, in combination, a base plate, a frame carried by said base plate, a stati pivoted in said frame, said base p'late having an aperture near said' staff, a permanent magnet carried by said base plate and having its poles located one on each side of said stati", a pointer carried by said stati' and projecting through said aperture, a dial carried by the side of said base plate opposite said magnet and cooperating with said pointer, an armature carried by said statil upon the opposite side of said Vmagnet from said base plate, a sup'port carried by said base plate independently of'. said frame, and a current coil carried by said support and surrounding said armature, the turns of said coil being interposed between the armature and magnet.

7. In an electric measuring apparatus, in

combination, a circular base plate, a bridge carried thereby vand having its legs flush with opposite edges of ysaid base plate, a current coil and a permanent magnet, one of 9ol Y which is carried by the bridge and the other yby the base plate, and a movable system carried by the base plate, saidmovable. system including an armature subjected both to the current coil and to the magnet and a pointer cooperating With a dial carried by the base plate, current terminals carried by said bridge, and a case enclosing all the parts recited and connected solely tol said bridge.

8. In an electric measuring instrument, in combination, a circular base plate, a frame carried by said base plate, a stati' pivoted between said frameand base plate, a permanent magnet carriedv by said base plate and having its poles facing each` other, one on each side of said staff, a dial carried by said base plate upon the side opposite to that whereon said magnet is located, a

iso

from the magnet poles, a bridge v carried by said base plate and traversing said magnet,

- current connections carried by saidbridge,

anda current coil supported by said bridge and surrounding said armature5 said coil lying entirely Iupon the side of said magnet opposite tosaid pointer and having its end portions disposed one at each side of said armature, the field of said coil being sub- 15 stantially perpendicular to the ield between Y said magnet poles.

vIn testimony whereof, We hereunto afix our signatures WALTER M. SCOTT. RALEIGH E. TRESISE. Y 

